TOOTH PREPARATION FOR CLASS II
CAST METAL INLAY
Part 1
Dr. JÚLIA NEMES
INDIRECT RESTORATION
Inlay, Onlay, Overlay
-Cast metal restoration
Gold 22 karat
Gold (platina) alloy
Ag-Palladium alloy
-Esthetic Inlay/Onlay/Overlay
Ceramic
Composite
-Metal-Ceramic
DECISION
THE STEPS OF MAKING INLAY
/indirect method/
1.
2.
3.
4.
5.
Preparation
Impression, Temporary filling
Tray-in (finishing, polishing)
Cementation
Finishing, polishing
Consideration of making metal inlay
►
In most cases we have to remove more toothstructure.
►
We can not leave big undercuts into the cavity.
►
The retention is macroretention /friction/
►
The place in direction is important. Orientation of the
bur! MOD
►
The occlusal contact with the antagonist tooth may not
be at the cavosurface margin of the inlay.
Class II preparationen for Metal Inlay
Class II Inlay involves the occlusal and 1 or 2
proximal surfaces. OD, MO, MOD
► Illustration:
upper premolar OD
OD :
1 occlusal Part
1 proximal Part
OD Cavity
► Bevor
and after
Primer (initial) preparation
Instrument:
- Speed, Handpiece
- Burs
► Tapered fissure bur
hard metal/ diamond
► With slightly rounded
angles
►
►
Conicity: 3-5 °
General rules
for occlusal box
► Width:The
occlusal extention is not more, than the
half of the vestibulo-orale distance between the cusps
► Depth: of the cavity is 1,5 mm.
► The outline form: includes the central fissures.
► Walls: have to diverge in occlusal direction.
The divergency of the walls depends on the depths of
the cavity, the length of the crown….. (3-5°)
► The contakt with the antagonist teeth may not be at
the area of cavosurface margin.
Occlusal Preparation
(execution)
► Bur
enters into the
fissure, close to the
involved marginal ridge,
a depth of 1,5 mm on
the occlusale cavity.
► Bur is held prallel to the
long axis of the tooth
crown.
► Orientation!
Upper arch
Lower arch
premolar
Occlusal preparation
► Making
the mesial
extension, we have to pay
attention not to remove
the dentin support under
the marginal ridge.
D
M
Occlusal preparation
-Preserve the strengths of the cusps
and its dentinsupport!
The vestibulo-orale walls of occlusal
cavity have to go around the
cusps, in mild curvature, and the
prepared isthmus has to be only
slightly wider, than the bur.
The dovetail retention form resist
distal diplacement of the inlay.
MO, OD
General rules
for proximal box
► The
extension of proximale carious lesion gives
the extention of proximale cavity.
► The contakt with the neigbouring tooth has to be
eliminate. (minimum distance of 0,5mm)
► Between the proximale laterale walls and the outer
elevation of the tooth has to be 40° degree.
► The divergence depends on the depths of the
cavity, the length of the crown.
► The gingival wall stays supragingival,
if it is possible.
Proximal Preparation
(execution)
Proximale ditch/cut:
1.We extend and widen the
preparation distally, untill
the enamel-dentin junction,
and we leave a small part of
occlusal enamel untouched.
2.We cut a dich, moving the
bur in facio-lingual and
gingival direction.
Proximal Preparation
►
►
►
►
Proximale ditch/cut: the mesiodistal width of the ditch should be
0,8 mm, and 2/3 (0,5mm) in
Dentin, und 1/3 (3mm) in
enamel.
We prepare gingivally, until the
caries and we extend the ditch in
vestibulo-orale direction
The proximal enamel will be
thinner, and thinner, and starts
breaking, if not we remove.
The ideal clearance with adjacent
tooth (minimum distance) of
0,5mm
Cavity after the primer preparation
Final (secondary) Preparation
► Removal
of any remaining infected dentin
and/or old restoration and Pulp-protection
► Preparation of cavosurface margins in different
angle (Preparation of bevels and/or flares)
- in occlusal cavity
- in proximal cavity
- on the vestibulo-oral walls
- on the gingival walls
► Secondary retentionselement:
proximal grooves, slot, skirt
► Finishing the walls
Final (secondary) preparation
Removal of any remaining infected dentin and/or old
restoration and Pulp-protection
With round metallbur (hard or steel)
(Calcium-hydroxid )+ Glassionomer
Final (secondary) Preparation
Preparation of occlusal cavosuface margin
(bevel or flare)
► The
enamel (cavosurface margin) must be prepare
in at about 140°. This should result in 40° marginal
metal on inlay.
► Flame-shaped, fine-grit diamond
► Cusp incline!
Final (secondary) Preparation
Preparation of gingival cavosurface margin in
the proximal cavity. (bevel or flare)
We have to tilt the flame
shaped, fine-grit diamond
mesially, to produce a
gingival bevel. It means a
30° marginal metall.
-In this case the thickness
of cement is thinner than
50 µm, at about 20µm.
-Enamel with dentinsupport
Gingival bevel:0.5-1 mm wide
Final (secondary) preparation
Preparation of proximal cavosurface margin
on the buccale, linguale Walls.
(bevel, flare)
► Proximal
cavosurface
margin has to result in
40° marginal metal,
and 140 ° marginal
enamel.
Final (secondary) Preparation
Secondary retention-element „proximal grooves”
In the proximal cavity
► Possibility!
► For
improving the retention.
We prepare in dentin,
parallel with the axio-pulpal
wall, between this wall and
the facial/lingual walls
►
„proximal grooves”.
Final (secondary) Preparation
Slot Preparation
Indikation:
MO Inlay/Onlay
OD
„
► Place of the slot:
is in Dentin (between the the Pulpa
and Enamel-Dentin junction.
► Bur:
► The extention of the slot:
- M-D Direction: the width of the bur
- F-L Direction: 2 mm
- Depth: 2 mm distance from pulpal
wall
►
„Skirt” prepararion
►
Skirt is a thin extension of
Skirt
metal inlay on the facial or
lingual proximal margins. The
preparation stays in the most
cases in enamel, if not it
removes very little dentin.
►
Retention form und Resistence
form will be improved.
►
The skirt extension is a
conservative method for
improving the retetion and
resistence form.
Not skirt
Final (secondary) Preparation
► Finishing
the walls and rounded
the line angles
-the flame shaped, fine-grit
diamond or
-metal-finising bur with 18,20 or
more cutting ages
Rounded the
axio-pulpal line
angle
Preparation of bevel on different cavosurface
margins (occlusal, gingival, and proximal)
Modification in Inlay-preparation
Indikacions:
► faulty occlusal grooves and/or fissures that is
continuous on facial/lingual surface
► healty grooves/fissures but the crown of the tooth is small
► Retention is not enought
Possibilities:
- Extension on buccal/oral surface, includes the fissure and
grooves into the cavity.
-minimal divergenc (2%)
-secondary retentionselement has to be prepared. Skirt,
slot, shoulder
Modification
faulty occlusal grooves and/or fissures
► Dentinsupport
► Only
beveling!
has to be preserved.
Modification
Facial or lingual surface groove Extension
►
Extension is till the
Caries.
Beveling in enamel.
Modification
Strong obligate ridge (crista transversa)
(MO caries )
►
We prepare MO cavity
-without skirt
-with skirt on the
palatal side
- no skirt on the buccal
side
►
Obligate ridge stays
untoucht
Modification
Strong obligate ridge (crista transversa)
(ODP
► We prepare OD cavity
-with skirt or without skirt
► Obligate ridge stays untoucht
Strong obligate ridge (crista transversa)
(MO, ODP,)
► Crista
transversa is strong, and healthy.
Capping only one cusps !
(Inlay)
►
Reason: the extension of occlusal caries is bigger,
than one half of the distance between the vestibularoral cusps.
►
Caries extended under the cusp
►
Lower first molar mesio-linguale cusps.
Lower first molar: mesio-linguale cusp
is reduced.
► Reduction
with contra-angle.
► See at onlay preparation.
caries
Lower first molar: mesio-linguale cusp
is reduced.
►
„proximal grooves” is prepared for improving retention (a)
►
Axio-pulpale line angle is rounded (b)
Where contraanlgle and skirt meet, the place has to be
rounded. (c)
►
a
b
c
Beveling or/and skirt (Flare)
2. Impresson, temporary filling
What kind of impression?
What kind of temorary filling?
Metal-Inlay/Onlay/Overlay
Preparation
Part 2
Dr. Júlia Nemes
DECISION
Inlay/Onlay/Overlay
/indirect method/
► Definition:
► Indication:
-Extension of caries is big (2/3 rule)
-Big undercuts in dentin, and cusps
-Rootcanal treated tooth
-Occlusal correction is needed
-Cusps-frakture
Onlay
► All
cusps are reduced.
Counterbevel
(Reverse bevel)
Exeption
Overlay
► Difference
in the preparation in case of the cusps.
► Cusp
reduction:
Collar with bevel (skirt)
collar (1 mm withs)
► Not cusp reduction
Difference in supporting, and non supporting cusps
General rules (onlay)
► Because
of the cusp reduction
decreases the retention, (shorter
vertikal walls), therefore the
secondary retentionselement are
required.
► For improving the retention, we
can prepare parallel with the
axio-pulpale wall „Secondary
Retentionselement”
Proximal grooves preparation
Class II cavity preparation for Metal Onlay
Lower 6, MOD caries (Class II)
case:
MOD :
1 occlusal cavity
2 proximal cavity